This invention relates generally to the field of speech recognition systems. In particular, this invention relates to in-vehicle speech recognition systems for controlling vehicle accessories.
Speech recognition systems on board automobiles permit drivers and passengers to control various vehicle functions by uttering voice commands. One or more microphones placed throughout the cabin and coupled to a speech processor receive the voice commands. The speech processor processes the uttered voice commands using various acoustic and language modeling techniques to correspond the uttered voice commands to known commands contained in one or more command grammar sets.
A major problem of existing speech recognition systems is accurately recognizing utterances of multiple speakers. This problem is especially prevalent in speech recognition systems used on board vehicles where multiple occupants, such as the driver, front passengers and rear passengers, issue voice commands. Thus, in-vehicle speech recognition system must be able to process audio signals corresponding to spoken commands issued from various locations within the cabin, both in the front and back seats. In many vehicles, particularly large automobiles, trucks and vans, the acoustic characteristics of the various seating locations can vary with the effects of traffic, window position and audio system sound. This variation in acoustic characteristics can have a noticeably adverse affect on the accuracy of the speech recognition system. Moreover, while simply placing a microphone proximate each seat may help improve overall recognition accuracy, it does not accommodate for the variation in acoustic characteristics at each seat.
Another problem specific to speech recognition systems in automobiles is selectively determining the vehicle functions that may be voice activated by various occupants of the vehicle. For example, in an automobile equipped with one or more voice activated rearview mirrors, permitting passengers to operate the mirror may be disadvantageous. As other examples, it may be desired that a rear seat passenger be prevented from operating a front window, or that a child passenger operate any window controls at all.
Accordingly, an improved in-vehicle speech recognition system is needed that can better recognize speech commands at various cabin locations as well as control which automobile accessories can be voice operated at these locations.